The invention relates to a device for fine blanking and forming a workpiece from a flat strip with several machining steps, comprising effective elements, including for example, punches and/or a forming element pressure pad for the shearing and/or forming element, V-shaped projections arranged at the pressure pad and a pressure plate of an upper part, and a cutting die, ejector, coining anvil and pressure plate of a lower part in one machining cycle, consisting of blanking, stamping, preforming and/or punching or the like, wherein the flat strip is clamped between the closed upper and lower parts and movable in a feeding direction (Z) in the open state of upper and lower parts.
The invention further relates to a method for fine blanking and forming a workpiece from a flat strip, wherein the flat strip is submitted to several successive machining steps comprising effective elements including, for example, a shearing punch and/or forming element, a pressure pad, V-shaped projections arranged at the pressure pad and a pressure plate of an upper part, and a cutting die, ejector, coining stamp and pressure plate of a lower part of a machining cycle, consisting of blanking, stamping, preforming and/or punching or the like, wherein the flat strip is clamped between the closed upper and lower parts to be machined and is sequentially moved forward in the open state of upper and lower parts.
Fine blanked parts with formed functional areas are mostly produced in progressive tools comprising several sequential steps. In this process, a cut out blank is taken up by a cross slide and led to the next machining stage when the tool is open.
A device is known from DE 21 65 224 A1 for continuous blanking a multitude of identical workpieces out of a metal sheet, strip or the like, in a multiple die press, which are interlocked into each other for the optimum utilization of the material, wherein a blanking stand is arranged to house a shearing punch and a correspondingly formed die-plate, which together form a cutting or blanking tool. A shearing punch and die-plate are connected to each other via mechanical elements which, after every cutting operation, advantageously, when the press ram crosses the upper dead center, independently cause a synchronous horizontal 180° turn of the shearing punch and die-plate. This is realized by executing half of the turning movement during the ascending and descending strokes of the press rams, respectively. The target of this turning movement is to achieve a material saving interlocking of the blanks.
Further known from DE 44 09 658 A1, is a tool combination for blanking machines, especially for different machining of window and door casement sections or the like, wherein each tool has a die-plate and a punching element driven by the punching machine and the respective application of the tools is restrictedly guided by the punching machine. The die-plates of the tools are connected to a complex construction unit and rotatably supported on an axis which coincides with the direction of the movement of the punching machine drive. The respective punching elements also form a construction unit. An effectice guidance is provided between the construction units that secures respectively uniform turning positions and allows for approach and retreat of the construction units.
Despite all of the measures according to the state of the art, material consuming excessive dimensions at designing the metal blank development have to be provided, especially in the case of smaller parts produced according to a multiple cut concept, to avoid an influence of the forming operations on the geometry of the pressed screen. Consequently, in case of small parts per stroke, waste costs emerge which are higher than the costs of the parts, because fine blanking of certain sections of parts consumes quantities of material which are too large.
A further disadvantage is that due to transporting the blanked parts by means of a cross slide, the tool has to be opened, so that the cross slide can transport the blanked part to the next machining stage. Due to this, the specific production time per part is increased. Furthermore, the rams of the press have to nearly go to their ascending or descending dead centers, which limits the quantity of strokes. Often left or not taken out by the cross slide, slugs in the tool area lead to additional stoppages of the production process and to damages at workpieces.
At this state of the art, it is an object of the invention to provide a method and a device for fine blanking of small to medium sized parts which make it possible to significantly save valuable materials, to combine the machining function of the active elements with the transportation function from one machining stage to the following machining stage increasing at the same time the quantity of strokes and the efficiency and to avoid stoppages of the production process caused by not removed from the tool waste.